The graph above shows the number of flights per month and clearly visualizes the size difference between the major airlines (American, Delta and United) and Alaska and Frontier.
Some notable data points can be observed when looking at this graph. First of all is September 2001 and the impact it had on the number of flights for every airline. We see Delta Air Lines dropping from 74892 flights in August 2001 to 60133 in October 2001. Interesting to note is that it did not seem to impact Alaska Airlines as much as it did Delta, American and United.
Another interesting point is happens in January 2010. This is when Delta Air Lines has a significant increase in the number of flights per month. This is when Delta Air Lines and Northwest Airlines officially merged and the Northwest brand officially retired. source: https://www.reuters.com/article/us-delta-northwest/delta-buys-northwest-to-create-biggest-airline-idUSTRE49S8BA20081030
We see a similar thing happening to United Airlines in January 2012 who merged with Continental Airlines. source: https://www.nytimes.com/2010/05/03/business/03merger.html
We also see the exact point when American Airlines officially merged with US Airways, April 2015. source: https://www.washingtonpost.com/business/the-last-days-of-us-airways/2015/09/25/f5530686-60a6-11e5-8e9e-dce8a2a2a679_story.html
On a smaller scale we see the merge from Alaska Airlines and Virgin America in April 2018. source: https://blog.alaskaair.com/alaska-airlines/company-news/virgin-america-alaska-single-operating-certificate/
The most interesting data point is likely January 2000, where there is a sudden spike in the percentage of cancelled flights. It could be the case that the Y2k had influence and airlines preemptively cancelled flights, however we could not find a source on this. As far as the airlines are concerned, American Airlines had the most cancelled flights relatively speaking for a long time, but has been overtaken this year by Frontier Airlines. Frontier had a low amount of cancelled flights for a long time but the percentage has been rising for the last couple of years. At the lower end we see Delta Air Lines having a low amount of cancelled flights.
Looking at the average departure delay in the history we see that since 2010 Alaska Airlines has consistenly had the lowest amount of departure delay. On the other side of the spectrum we find Frontier Airlines, which consistently has had the most average departure delay. Interesting is that the average departure delay has increased since 2017. Whereas before it could be said that Frontier was comparable to American, Delta and United, it has since grown a gap to those other airlines. As far as the average arrival delay, Alaska and Delta Airlines seem to be the best performing in 2018. Though it should be noted that the airlines seem to be more closely matched in this category. However Frontier is still the worst performing in this category. Also looking throughout the history, Frontier seems to be the airline with the most average arrival delay. Delta and Alaska have the least amount of average arrival delay throughout its history.From the plot shown above it is difficult to show that one airline is better than the other. On the other hand we do see a pattern across all airlines. During the winter period (December till March) we see that the majority of flight cancellations is due to the weather. This should not really come as a suprise, since bad weather that would influence airlines is more likely during the winter as opposed to the summer. This can be an interesting point to follow up on in future work.